All Creatures Great and Small Series 4 interview and new trailer: Nicholas Ralph and Rachel Shenton on James and Helen's baby dilemma and missing Tristan

But, as viewers will learn when series four of All Creatures Great and Small launches on Channel 5 on Thursday, October 5, Helen and James have a dilemma. Is now the right time to start a family, not knowing whether or not James will be called up?

“They are broody,” says Nicholas Ralph, who plays James Herriot. “Helen is maybe more upfront about it. James is slightly more guarded, as is often the way. Deep down, James certainly knows what he wants but yes, there’s this constant battle of heart and mind.”

Rachel says: “That’s a difficult one for them to navigate in different ways throughout the series – but that’s really all we can say.”

The series was filmed in the Dales over spring and summer, with the village of Grassington as Darrowby and the exterior of Skeldale House, where Helen and James, Siegfried (Samuel West) and Mrs Hall (Anna Madeley) live. Sadly, one important house member is absent, with Tristan (Callum Woodhouse) having answered the call of duty.

James, says Nicholas, is missing his best friend – “His almost brother in this surrogate family, and then, practically, it means he’s doing a lot more work day to day.” So he hirse an intern. “He thinks it’s going to be brilliant, he’ll bring this guy in, he’ll be a mini-James,” says Nicholas.” It turns out not to quite be that way. Richard Carmody comes along - he’s a character in the books - and he turns out to be a mini-Siegfried.”

Tristan is far from forgotten. Rachel says: “Siegfried is very much missing him, not that he wants to admit it. Helen is missing having that person to wink at across the table and roll her eyes when Siegfried is doing something, and Mrs Hall misses feeding him. So everyone at Skeldale is missing Tris, and the same goes for Cal, really, although we still WhatsApp and send messages, so he’s very much kept in the loop.”

New recruits James Anthony-Rose, who plays Richard, and Neve McIntosh, who plays bookkeeper Miss Harbottle, are filling the void. “Two great additions to the show, very much bringing a different dynamic,” says Rachel. “Neve comes in and ruffles feathers in episode two. Nobody really knows what to make of her, and it’s good fun - it’s like another injection of energy. It feels fresh.”

Nicholas: “It's a little bit of art imitating life. I could give Jamie little pointers here and there about the animal stuff. And with him being new, like I was, to the world of television, I could give him the odd little pointers here and there as well with regards to that. He’s slotted in so well.”

The series wrapped production on location in July. The interior scenes are filmed at a unit in Summerbridge, but Grassington is famous as the village that gets a vintage All Creatures makeover in the summer, and visitors from around the world turn up on filming days to see the action and, hopefully, some of the cast. “Sometimes they have to move the crowd,” says Rachel. “They sort of shimmy them round as they move wherever they are shooting, but everyone is super-supportive and lovely, so you’ve never got any complaints.”

Nicholas says: “We couldn’t do it without the support of the local communities in the Dales. They are so welcoming, people are just lovely. Obviously, it always came with the caveat ‘don’t muck it up, because these stories mean a lot to us’, and the BBC show was so loved. They really take pride in the Dales, in their part of the world.”

Rachel adds: “It doesn’t matter where we pitch up, everyone is nice and welcoming. Long may that continue, I guess.”

Indeed. And what All Creatures fans really want to know is, will there be a fifth series? “I wish we knew. I couldn’t tell you if I wanted to, I’m afraid,” says Rachel. “No idea,” says Nicholas.

Earlier this year, Rachel starred in Channel 5’s psychological drama For Her Sins, playing a most un-Helen-like character. “I had so many people say, ‘what would James say about that?’,” she says.

Nicholas has a second film about CS Lewis in the pipeline (he played the writer in The Most Reluctant Convert, released in 2021), and another American series coming up that he cannot say too much about. He is currently narrating the fifth and final All Creatures audiobook. “I feel like Nick forensically knows those books, he’s always our point of reference,” Rachel says.

Both feel blessed to work in such beautiful locations, although they have their favourites. Rachel: “My favourite always, just because one of my first scenes was shot there, is Yockenthwaite, Heston Grange, Helen’s farm. I love being up there. I think I’m one of the few people that do because it’s got its own weather system. You’ve also got no phone signal so unit base cannot communicate.”

Nicholas says: “Arncliffe, the back of our Skeldale House – I absolutely love it, and we spent quite a lot of time up there. Grassington, obviously, and we were at Broughton Hall for Mrs Pumphrey and the wonderful Patricia Hodge – we had her a little bit more this year. And we also had a new place, which is beyond Arncliffe – we were at a farm.”

The cast did manage to find some downtime while filming, with visits to Bettys and Ilkley Playhouse. Nicholas says: “I went out to Ilkley golf course – it’s very nice, the first seven holes are along by the river – it’s stunning out there.”

Last year they got to know some VIP friends of the series. When James and Helen married in series three, in attendance were Jim Wight and Rosie Page, children of the real James Herriot, Thirsk vet Alf Wight, and his wife, Joan. Rachel says: “It was a bit strange at first – ‘we’re playing your mum and dad, I hope we get it right’ – but they have been incredibly supportive.

“I’ve got a great relationship with Rosie in particular, and I email her and call her if I’ve got questions, because obviously the books are written from Alf Wight’s perspective, so we meet Helen through his eyes.

“I’ve taken bits from the book and bits that Rosie told me, and created Helen myself, so she’s been instrumental in that, and always been so gracious in sharing stories. What continues to be magical when she is telling me those things is what an incredible and rare union the real James and Helen had.”

Nicholas says: “We do have their seal of approval on matters, which is just priceless. I’ve done little things with Jim as well. In-between series we did a little thing for Channel 5 last year when we went to the museum (The World of James Herriot in Thirsk). We just hung out for a day doing that.”

Rachel: “It adds to the richness because obviously the world knows the books, the world knows the stories, but to get that peep behind the curtain from two people that, nobody in the world would know them better than, is really special, and some of the anecdotal stories I hear about Helen that the rest of the world doesn’t get to hear, about how she’s a bit cheeky.”

Nicholas adds: “And they do affect the scripts – what they bring to the table is their thoughts and feelings. It adds to that authenticity.”

Rachel says: “Visiting that museum that day in Thirsk, Nick, I don’t know about you, but I don’t think I appreciated or maybe understood the level of impact the stories have had worldwide. There is one room full of newspaper articles from all over the world about the stories and you’re like, my goodness, I can’t believe we are part of this.”

• All Creatures Great and Small returns to Channel 5 on Thursday, October 5, at 9pm. The series will also be available to stream weekly on My5 and catch up of series 1-3 is available now.